This invention relates to a method for preparing highly active and selective fine particle catalysts for low pressure hydrocracking reactions. More particularly, the invention relates to an improved catalyst and method of producing such active catalysts by a reaction of an iron (III) oxide and elemental sulfur in the presence of a hydrogen donor.
Although iron and other transition metals have been used as dispersed-phased catalysts in various processes for the hydrogenation and liquifaction of coal, the present invention is an improvement thereof in that the new catalyst is a very active form that can be prepared as a slurry of unsupported fine particles and stored for several days prior to use. Heretofore, catalytic systems were required to be prepared either in situ or to be used immediately upon preparation thereof.
An advantage of this catalyst is the potential for use with once through catalytic contact with coal or other substrates because these catalysts have high initial activity and can be used in small concentrations. Representative processes of coal supported iron catalysts obtained are described by coal impregnation in U.S. Pat. No. 3,775,286 to Mukherjee et al. and various publications such as the Mukherjee et al. "Catalytic Roles of Iron and Hydrogen Sulfide on Hydrogenation of Coal", Fuel, Vol. 63, May, 1984. In this prior work, hydrogenated oxide was precipitated from solution by the addition of ammonium hydroxide onto particulate coal and suspension. The intimate mixture of iron and coal could then be drained of excess moisture, dried and subjected to hydrogenation or direct liquefaction of the coal. In the article quoted above, coal was hydrogenated in batches with and without added sulfur in the presence and absence of iron oxide as a catalyst at elevated temperatures of about 400.degree. C. and at elevated pressure. Work by Cugini, et al. with small quantities of iron salts impreganted in coals provided good coal liquefaction results. (Reprints, ACE Division of Fuel Chemistry 1991, 36 (1), 91.
Other workers have prepared catalyst precursors for carbonaceous material processing in which hydrogen sulfide or a metal sulfide such as cesium sulfide is reacted with hydrated iron oxide to form a catalytically active iron quantities of iron salts impregnated in coals provided good coal liquefaction results. (Reprints, ACE Division of Fuel Chemistry 1991, 36 (1), 91.
Other workers have prepared catalyst precursors for carbonaceous material processing in which hydrogen sulfide or a metal sulfide such as cesium sulfide is reacted with hydrated iron oxide to form a catalytically active iron oxide which is usually prepared in situ and used immediately in the direct liquefaction of coal.